JPS605476A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To use effectively even a track having a drop-out by dividing a piece of track into plural sections to record the same data to each section and replacing a track having a drop-out with the reproduction signal of another section in a reproduction mode. CONSTITUTION:A data signal track 3 is set at the most inside circumference of a magnetic disk 1 and divided into two parts by 180 deg.. A divided signal generating circuit 10 which divides the track 3 is provided to record the same data signal to those two divided areas. In a reproduction mode the signals on the track 3 is read out by a magnetic head 4 and amplified by a reproduction amplifier 15 in the form of a reproduction signal 29. Then the smplitude noise of the signal 29 is deleted by a limiter 16, and the signal 29 is given to an FM data demodulator 18 to obtain a coded signal 31 corresponding to the coded signal 27 of a record mode.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a video signal magnetic recording and reproducing device using a rotating magnetic disk, and in particular to a magnetic recording and reproducing device using a rotating magnetic disk, in which a video signal track and a data signal track are provided on the same magnetic disk. The present invention relates to a recording/reproducing device.

Prior Art Generally, a video signal recording and reproducing device using a magnetic disk uses one track for each still image, and can record a plurality of still images on one disk. At this time, if a still video track and a data signal track are provided and recorded on one disk, playback becomes possible, which is very convenient. However, in recording and reproducing using a magnetic disk, changes in the touch between the magnetic disk and the magnetic head, as well as dust and scratches on the magnetic disk, can cause signal loss called dropout. Correction for this is required.

In magnetic recording of video signals, it is common to record video signals by FI'lI modulation, and this is usually used. However, in the case of FM modulated video signals, the dropout portion is located horizontally on the playback screen. It can be used even on tracks with dropouts, without changing the overall video content. However, in actual VTRs, etc., the reproduced picture is unsightly if left as it is, so by correcting the dropout period by replacing the dropout period with a normal reproduction signal one horizontal period earlier using the vertical correlation of the video signal, etc.
This prevents deterioration in the quality of reproduced images.

However, since the data signal is digital information and each bit has different information, it is not possible to use the same correction method as for video signals. For this reason, in a digital signal recording/reproducing device using a magnetic disk, such as a floppy disk, data on the quality of each track is recorded in advance on the outermost track, and defective tracks are determined based on this data. I try not to use the parts that are. However, it is extremely rare for a dropout to occur over the entire circumference of a track, and it is inefficient in terms of recording density to make an entire track unusable due to a dropout at one point on the track. not good. In particular, when video signal tracks and data signal tracks are mixed on the same disk, the above method
This results in a decrease in the number of still images and the amount of recorded data, making it very inconvenient to use. To avoid this, it is necessary to take measures against data signal dropouts with good track utilization efficiency.

<Object of the Invention> The present invention focuses on the above points, and provides a magnetic recording/reproducing device in which a video signal track and a data track are provided on the same magnetic disk, while minimizing reduction in recording density. A magnetic recording/reproducing device with improved signal reliability is provided.

<Embodiment> When recording data signals on a magnetic disk, the present invention divides one recording track into a plurality of sections and records the same data signal in each section, thereby eliminating dropouts. This is a method that makes it possible to use a trough with dropouts at the same time to improve track utilization efficiency.Furthermore, at the start of recording, the presence or absence of dropouts on the magnetic disk is determined in advance. Based on this, data signal tracks are provided in areas without dropouts, thereby making it easier to coexist video signal tracks and data signal tracks on the same disk.

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 is a diagram showing the track pattern on the magnetic disk in this embodiment, Figure 2 is a block diagram of the recording/reproducing part, and Figure 3 is a diagram showing the track pattern on the magnetic disk in this embodiment.
The figure is a signal waveform diagram of each part in FIG. 2. In this embodiment, the data signal track 3 is provided on the innermost circumference of the magnetic disk 1, and the number of divisions of the track is two, each divided by 180 degrees.

In FIGS. 2 and 3, data 26 to be recorded is applied to a coding circuit 5 and converted into a code signal 27 such as NRZ or MFM. This code signal 27 is further applied to the FM modulator 7 through the video/data changeover switch 6, subjected to frequency modulation, and amplified by the recording amplifier 8. The amplified FM modulated output 28 is applied to the magnetic head 4 and recorded on the data signal track 3 of the magnetic disk 1.

The four-magnetic head motor 14 and the servo circuit 13 control the rotation speed to a constant rotation speed, for example, 3600 rpm.

Here, when recording on the data signal track 3,
In order to divide the track into two as described above and record the same data signal on each, a division signal generating circuit 10 for dividing the data signal track is provided. The divided signal generation circuit 1
0 is coupled to a servo circuit 13, which forms a data track division signal in synchronization with the rotation of the magnetic disk 1, controls the encoding circuit 5 with the data track division signal, and extracts a data signal for recording. , the same data is repeatedly recorded in divided sections on one track.

In this embodiment, recording is performed twice on a 180-symmetrical circumference.

During reproduction, the signal on the data signal trunk 3 of the magnetic disk 1 is read by the magnetic head 4, and after being amplified by the reproduction amplifier 15 as a reproduction signal 29, amplitude noise is removed by the limiter 16, and the FM data is A coded signal 31 corresponding to the coded signal 27 at the time of recording is obtained by being applied to the demodulator 18.

In reproducing the video signal, the reproduced signal output from the limiter 16 further passes through the FM video demodulator 17 and is demodulated to form the reproduced video signal 30.

The reproduced coded signal 31 outputted from the FM data demodulator 18 is stored in RAMs provided in advance at least as many times as the number of track divisions, in this embodiment, the first RAMI 9, the second RA
M2.0, one section corresponds to one RAM, and is written and stored respectively.

On the other hand, the output signal 29 of the reproducing amplifier 15 is also given to a dropout detection circuit 23, which determines the presence or absence of dropout from the output signal 29, and supplies an output pulse 36 as a result of the determination to the RAM control circuit 24 as a control signal. RAM
The control circuit 24 controls the writing and reading operations of the RAMs 19 and 20, and outputs a RAM switching signal 37 to control the RAM selection circuit 21. The RAM selection circuit 21 switches whether to use the read signal 32 of the first RAM 19 as a data signal or the read signal 33 of the second RAM 20 as a data signal using a RAM switching signal 37 formed based on the dropout detection result. It is input to the code demodulator 22 of the stage. That is, as shown in the RAM read signals 32 and 33 in FIG. 3, if there is a dropout, the data read from the other section every time there is a dropout is used as the output signal 34 of the RAM selection circuit 21, This is input to the code demodulation circuit 22 to reproduce the original data signal 35.

Here, in the above-mentioned recording/reproducing apparatus, a magnetic disk l is inserted at the time of starting recording.
The dropout detection circuit 23 determines in advance whether or not there is a dropout for each track of Recording in the head 4 is controlled by matching the type of recording signal supplied to the head 4 and the track with a dropout held in the track selection circuit 11 so that a certain track is used as a video signal track. It can also be configured to do so. Reference numeral 12 denotes a track moving motor that moves the head 4 based on the output of the track selection circuit 11. By detecting tracks with dropouts in advance and using such tracks as video signal tracks, it is possible to improve the efficiency of track utilization and to improve the reliability of data signals. .

In addition, when dividing a track into multiple sections due to dropouts as described above, the number of divisions is changed depending on the situation where dropouts occur, and by setting the number of divisions to a number that can reduce the impact, the condition of the magnetic disk can be adjusted. Data signals can be recorded and reproduced using a recording pattern suitable for the data signal, and data signals can be recorded and reproduced even on tracks with dropouts without impairing reliability.

Effects> As described above, according to the present invention, by dividing one track into a plurality of sections and recording the same data in each section, it is possible to prevent dropouts on the track during playback. Even if a dropout occurs, it can be used in place of the reproduced signal from another section during that time, and can be used effectively even on tracks with dropouts. In addition, when using a magnetic disk, the reliability of data signals can be improved by determining the presence or absence of dropouts for each track in advance and using tracks with dropouts as video signal tracks. All l/racks on the same magnetic disk can be easily mixed and used as video signal tracks and data signal tracks without damage.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a recording track pattern of a magnetic disk in an embodiment of the present invention, Fig. 2 is a schematic block diagram of a recording/reproducing system, and Fig. 3 is a main point 1 of Fig. 2: Magnetic disk , 2: video signal track, 3: data signal track, 4: magnetic head, 5: coding circuit, 6: video/data changeover switch, 7: FM processing circuit, 10° data division pulse circuit,
11 Ni-Drack selection circuit, 12 Ni-Drack movement motor, 16: Limiter, 17: FM video demodulator, 18: F
M data demodulator, 19: RAM, 20: RAM,
21: RAM selection circuit, 22: code demodulator, 23 nitrosobout detection circuit, 24: RAM control circuit agent Patent attorney Aihiko Fukushi (and 2 others) Figure 1

Claims (2)

[Claims] (1) Using a rotating magnetic disk, a video signal track and a data signal track are provided on the same disk, and the above two signals are mixed track by track and recorded on the same magnetic disk. Of the plurality of recording tracks on the magnetic disk, only the data signal recording track is recorded in the apparatus.
A magnetic recording/reproducing device characterized in that each track is divided into a plurality of sections on the circumference, and the same data signal is recorded in each section of one track. (2) The recording device is provided with means for determining in advance whether there is a dropout on a track of the magnetic disk, and a track in which a dropout is detected by the output of the determination means is used as a video signal track. A magnetic recording and reproducing device according to patent scope (1), characterized in that: